Each iothub-explorer command has its own help that can be viewed by passing help the command name:

$ iothub-explorer help create
Usage: iothub-explorer create [options] [device-id|device-json]
Create a device identity in your IoT hub device registry, either using the specified device id or JSON description.
Options:
-h, --help output usage information
-a, --auto create a device with an auto-generated device id
-cs, --connection-string show the connection string for the newly created device
-d, --display <property-filter> comma-separated list of device properties that should be displayed
-l, --login <connection-string> connection string to use to authenticate with your IoT Hub instance
-k1, --key1 <key> specify the primary key for newly created device
-k2, --key2 <key> specify the secondary key for newly created device
-r, --raw use this flag to return raw JSON instead of pretty-printed output
-x, --x509 generate an x509 certificate to authenticate the device
-dv, --daysValid number of days the x509 certificate should be valid for
-t1, --thumbprint1 <thumbprint> specify the primary thumbprint of the x509 certificate
-t2, --thumbprint2 <thumbprint> specify the secondary thumbprint of the x509 certificate

Examples

Working with the device identity registry

Supply your IoT hub connection string once using the login command. This means you do not need to supply the connection string for subsequent commands for the duration of the session (defaults to one hour):